THE hit BBC series Line of Duty returns to our TV screens for a sixth outing this month, packed with jaw-dropping twists, shock betrayals, grisly crime scenes, marathon interrogations – and, yes, those delectable Ted-isms – that we all love.

Here, we list some of the myriad reasons why Jed Mercurio's award-winning police procedural has become such compulsive viewing. Buckle up.


The stalwart trio of Martin Compston, Vicky McClure and Adrian Dunbar, who play DS Steve Arnott, DI Kate Fleming and Superintendent Ted Hastings respectively, are the dogged team whose job at the anti-corruption unit AC-12 is rooting out "bent coppers".

Their camaraderie is testament to a strong friendship and mutual respect built off-screen. When filming in Belfast, Compston, McClure and Dunbar are usually neighbours. Dunbar has said his flat is where they eat, McClure's flat is where they learn lines and Compston's flat is the party pad.

In an interview with The Herald last year, Compston admitted this was a fair summary, saying: "That's mainly because I cannae cook, so I have to do something. It's fair to say, I'm quite sociable, but those two are as well. Vicky runs and organises our lives, Aidey does the cooking."


Superintendent Ted Hastings heads up AC-12 and Dunbar has revealed he drew inspiration from the style of great Scottish footballing managers such as Jock Stein, Bill Shankly and Alex Ferguson when breathing life into the character.

"He has a good man management style and sense of morality," he said. "That kind of character who has a way with people and they trust him. They know that, ultimately, even if it is to his own detriment, he will always do the right thing."

HeraldScotland: Adrian Dunbar filming series six of Line of Duty. Picture: World Productions/BBCAdrian Dunbar filming series six of Line of Duty. Picture: World Productions/BBC

The bold Ted has garnered quite a following for his phraseology and quick one-liners ("Hastings – like the battle!") with Enniskillen-born Dunbar deftly introducing a clutch of Northern Irish colloquialisms such as "fella" and "now we're suckin' diesel" that didn't appear in the original scripts.

Other gems from Ted over the years include the no-nonsense "Go back to the coal face, the pair of you, unless you've got more egg-sucking tips for your granny" and wry pub banter such as "Got you a big pint of that cat's p*** that you young fellas seem to like so much".

Not to forget the now legendary catchphrase: "Mother of God!"


The identity of "H", the corrupt and shadowy entity with a hand in almost every diabolical conspiracy running through the BBC drama since it began in 2012, has become the subject of feverish speculation among fans.

A recent revelation has been that, rather than one H, there are four. If that theory checks out, then three have been apprehended but one remains at large.

READ MORE: Line of Duty star Martin Compston on filming during a pandemic

Over the show's run we have met a slew of characters whose names bear the initial H. Such as Assistant Chief Constable Derek Hilton, Detective Chief Inspector Roz Huntley and Detective Chief Superintendent Lester Hargreaves – nasty pieces of work, one and all.

Then there is the row of mugshots seen pinned to a board in the offices of AC-12, a clutch of senior and high-ranking police officers whose acquaintance we are yet to make but who all have "H" surnames. And, of course, H for Hastings. Please Ted, no.


Let's face it: DS Steve Arnott isn't always the most likeable character. In short, if he was chocolate, he would eat himself. Or as Compston himself has said: "That's why I put him in waistcoats all the time, because he's that overdressed w***** in a call centre."

Yet, almost like a character in their own right, DS Arnott's natty waistcoats have a commanding on-screen presence. One of these days they will land their own spin-off show, mark my words.

HeraldScotland: Martin Compston, Adrian Dunbar and Vicky McClure in Line of Duty. Picture: Peter Marley/World Productions/BBCMartin Compston, Adrian Dunbar and Vicky McClure in Line of Duty. Picture: Peter Marley/World Productions/BBC


When you hear the distinctive beep – or that should be beeeeeeeeeeeppppppppppp – of the digital interview recorder, aka the DIR, being started, then get comfortable, an epic interrogation is about to unfold.

For the Line of Duty cast, these can be gruelling and mentally taxing scenes to shoot. According to Dunbar: "Those things are very tough. I have to learn sometimes 25 pages at a time. The takes can last 20 minutes – we do big, long takes."

The high intensity and pressure of these demanding segments can often lead to "corpsing" – acting parlance for descending into unscripted mirth – to occur mid-take.

Or, sometimes, it could be because McClure has sneakily scrawled a rude image in Compston's police notebook.

McClure recently told That Gaby Roslin Podcast she had played a prank on Compston by drawing a penis inside the prop being used by her co-star. Only when the cameras started rolling did Compston notice the doodle.

McClure said: "It's stupid, so childish and it's not funny for anyone else!" Compston added: "It happened again this year. They just gave me the same notebook. It's just a random page and I just opened it…"


Around 10pm on a Sunday evening there comes a collective intake of breath as the nation gasps at whatever magnificent cliffhanger the latest episode has ended on. Only to then spend an entire week, wishing away the hours, until Sunday night at 9pm rolls around for the next instalment.

READ MORE: Line of Duty star Adrian Dunbar on playing Superintendent Ted Hastings

In a world of box set binges and on-demand streaming, there is something hugely refreshing about this old school style of viewing. Even if it drives us half batty at times.


Lennie James, Keeley Hawes, Daniel Mays, Thandie Newton and Stephen Graham are among the stellar names to have graced our screens to date.

The new series will see Trainspotting and Boardwalk Empire star Kelly Macdonald play DCI Joanne Davidson, billed as "the most enigmatic adversary AC-12 have ever faced".


Line of Duty has carved a reputation for its love-to-hate-them villains. Take DI Lindsay Denton, played by Hawes, who despite her cool-as-ice persona and dastardly deeds, is testament to the skill of the show's creator and writer Jed Mercurio at conjuring relatable characters from murky shades of grey.

HeraldScotland: Kelly Macdonald as DCI Joanne Davidson in Line of Duty. Picture: Steffan Hill/World Productions/BBCKelly Macdonald as DCI Joanne Davidson in Line of Duty. Picture: Steffan Hill/World Productions/BBC


Be it OCG (organised crime group), ARV (armed response vehicle) or UCO (undercover operative), the AC-12 team love an acronym.

Best brush up on all of those if you don't want served with a "Reg 15". That's a Regulation 15 notice which advises an officer that a complaint has been made or a matter has come to light that warrants an investigation by the professional standards department.

But remember, if you do get hauled in, you have the right to be questioned by an officer at least one rank senior.


Showrunner Mercurio – a former hospital doctor and Royal Air Force officer before he turned his hand to telly – is a fiendish genius when it comes to gripping, twist-laden storylines where you never quite know who will live and die.

READ MORE: 10 exciting new thrillers perfect for escapism and adventure

Even the main cast of Line of Duty admit to trepidation when the scripts arrive for a new series, wondering if their character might be killed off.

Who will be left standing at the end of series six? Guess we will need to tune in and find out …

Line of Duty returns to BBC One on Sunday, March 21 at 9pm